1. Field of the Invention
The present invention relates generally to tidal and wind power generators which can be used not only as tidal power generators but also as wind power generators and, more particularly, to a variable blade type tidal and wind power generator with increased generation efficiency which includes rotor blades configured such that each rotor blade is spread at a first side at which it receives the wind, and is folded at a second side spaced apart from the first side at an angle of 180° so that, when the rotor blade is rotating, air resistance can be minimized and the wind can be collected by the rotor blades, and which is configured in such a way that the number of generation units operated to generate electricity is changed depending on the magnitude of the wind, whereby the generation efficiency can be further enhanced, and which is able to be easily installed regardless of installation place and is configured such that a plurality of wind power generators are stably and reliably installed even in a comparatively small space by a simple method, whereby the power production per a unit area can be maximized, so that the generator can be easily industrialized.
2. Description of the Related Art
Generally, power generation methods which are now in use include thermal power generation which uses a large amount of fossil fuel, nuclear power generation which uses uranium, water power generation which requires a large scale of plain freshwater equipment, etc. Such power generation methods are major contributors to air pollution or global warming, create intractable radioactive waste, or cause severe destruction to the environment. Therefore, more environmentally friendly power generation methods are urgently required. As representative examples of such substitute environmentally friendly power generation methods, solar power generation and wind power generation are widely being studied. Particularly, recently, wind power generation which uses the force of the wind is most preferred. In Korea which is surrounded by water on three sides, interest in wind power generation is largely increasing.
Wind power generation which uses the force of the wind is a technology which uses the aerodynamic characteristics of kinetic energy of flowing air and rotates a rotor to convert the energy into mechanical energy, thus producing power. Wind power generators are classified into a horizontal type and a vertical type according to a direction of a rotating shaft with respect to the ground. Such a wind power generator includes a rotor which has a hub and blades, an accelerating unit which accelerates the rotor and operates the generation unit, a control unit which controls the generation unit and different kinds of safety devices, a hydraulic brake unit, a power control unit and a steel tower.
Furthermore, wind power generation is a new energy generation technology which has a minimal effect on the environment because it uses nonpolluting, ubiquitous and infinite wind as the energy source, and it makes it possible to efficiently use the territory and to compete with existing power generation methods in power generation cost if a large power generation complex is constructed.
Such a wind power generator converts kinetic energy of a rotor which is rotating into electric energy. Here, in theory, about 60% of kinetic energy of the wind is converted into mechanical energy, and much energy loss is also caused during a process of converting the mechanical energy into electric energy. Therefore, efficiency in conversion of the energy of the wind into electric energy is merely 20% to 40%, although it slightly varies depending on the shape of the rotor.
The conventional wind power generator is problematic in that only when the speed of the wind is higher than a predetermined value and the density of air is comparatively high can the rotor be rotated by kinetic energy of the wind transmitted to the rotor blades so that the rotor rotates to convert the kinetic energy of the wind into electric energy.
In other words, in the conventional wind power generator, if the wind blows lightly, the rotating force of the rotor is greatly reduced, and it may be impossible to generate electricity.
Particularly, in the case of the conventional wind power generator, when each rotor blade rotates by 180° from a side at which it receives the wind, the rotor blade acts to impede the rotation of the rotor because of resistance of the wind. Thereby, the generation efficiency is further reduced.
In an effort to overcome the above-mentioned problems, a rotor having variable blades for wind power generators was proposed in Korean Patent Registration No. 0966523.
As shown in FIGS. 1 and 2, the rotor having variable blades for wind power generators of No. 0966523 includes: a casing 110 which is coupled to a rotating shaft of a generator and is rotated along with the rotating shaft; blades 120 which are provided around the casing 110 at positions spaced apart from each other with respect to the circumferential direction and the longitudinal direction at regular intervals so as to rotate the casing 110 using the force of the wind and are spread or folded by the force of the wind; brackets 131 to which the blades 120 are rotatably mounted by hinges, and which are installed on the casing 110; and drive units 130 which are installed on the casing 110, and to which the blades 120 are rotatably mounted. The drive units 130 operate the corresponding blades 120 in such a way that the blades 120 are spread or folded depending on the direction in which the blades 120 receive the wind. Each drive unit 130 includes: a bracket 131 which is installed on the casing 110, and to which the corresponding blades 120 are rotatably coupled by hinges H; a cylinder 133 which is installed on the bracket 131 and defines an operation space 133a therein; a piston 135 which is disposed in the operation space 133a and linearly reciprocates; a compression spring 137 which is disposed in the operation space 133a to elastically bias the piston 135 towards the blades 120; and links 139 each of which is connected at a first end thereof to the corresponding blade 120 and is connected at a second end thereof to the piston 135. While the rotor 100 rotates, when front surfaces 121 of the blades 120 face the wind, the blades 120 are spread. When rear surfaces 123 of the blades 120 face the wind, the blades 120 are rapidly rotated on the bracket 131 and folded by the wind power and the elastic force of the compression spring 137 so that wind power applied to the blades 120 can be reduced. In this way, the rotating force of the rotor 100 can be increased.
Although the rotor 100 having variable blades for wind power generators of No. 0966523 is configured such that the blades 120 are spread or folded by the wind, because the blades 120 which have been in the spread or folded state are converted into the other state when they are rotated around the casing 110 by 180°, there is the possibility of the blades 120 being not reliably spread or folded. Further, because the elastic force of the compression spring 137 which folds the blades 120 acts as force to impede the rotation of the rotor 100, the generation efficiency of the generator is not enhanced as expected.
Furthermore, the rotor 100 having variable blades for wind power generators of No. 0966523 does not have a separate means for making repair or maintenance possible without stopping the rotor 100. Thus, repair or maintenance of the rotor 100 cannot be easily performed. That is, even if any of the blades 120 malfunctions, because the rotor 100 is continuously rotating, it is not easy to repair the malfunctioning blade 120 after interrupting the operation of the rotor 100.
In addition, the conventional wind power generator uses a single turbine to generate power regardless of the magnitude of the wind. Thus, even if the magnitude of the wind is largely increased, the generation quantity cannot be increased over a predetermined level.